The periodic table is split into parts – groups, periods, and blocks. Each group, period, and block shares similar physical and chemical properties and undergo similar reactions. In this article, the focus is on the properties of a family of metals called transition metals.
When you began chemistry, one of the things that caught your attention was metals that form colored complexes and exhibit a kind of magnetism. These metals are transition metals, and these are some of their properties.
The physical properties, chemical properties, and reactions of these metals set them apart from other elements of the periodic table. Their uniqueness has also brought them into various industries, fitting into simple to complex applications.
What are transition metals?
Transition metals occupy the middle portion of the periodic table, located between groups 3 and 12. These elements sit in the d-block of the periodic table. Therefore, they have partially filled d orbitals.
Going down on the periodic table, a group of elements known as the lanthanides and actinides are another set of transition metals called the inner transition metals. These elements originally belong to the f-block, but their d orbitals are partially filled before the f orbitals.
There are 38 transition metals. But, some classifications have 40, lawrencium and lutetium inclusive.
What are the physical properties of transition metals?
High tensile strength
Transition metals have strong metallic bonds because of their partially filled d orbitals. These strong bonds also make these metals have high density. The bonds form a lattice structure that helps the atoms together, thereby making them highly durable.
High melting and boiling points
The strong bonds within these metals require high amounts of energy (in the form of temperature) to break. The partially filled d orbitals create a “sea” of electrons that hold the metal ions together by strong intermolecular forces.
In addition, despite the high temperatures and the breaking of these bonds, transition metals do not change phase.
Metallic luster
Transition metals are known for their characteristic metallic luster. Their shiny appearance is due to the interaction between light and the delocalized electrons in the d-orbitals.
When light falls on the metal surface, the electrons absorb and re-emit photons, which is the shiny, reflective appearance of the metals.
Thermal conductivity
The delocalized electrons in the d orbitals of these metals are mobile. Their constant movement causes a flow of electrical current. This makes transition metals good conductors of heat and electricity.
They are useful in electrical wiring and the manufacture of electrical fixtures and equipment.
Malleability and ductility
While you can adjust the forms and structure of items made with transition metals, it is difficult to break them. The movement of electrons in the metal lattice is a way these metals withstand mechanical stress and do not break.
Magnetic properties
Transition metals are paramagnetic because they have unpaired electrons in their (n-1) d orbitals. Paramagnetism increases from left to right across transition metals as the number of unpaired electrons increases.
Transition metals are also ferromagnetic. They are attracted to magnetic fields and can maintain this attraction even after removing the external magnetic field.
Elements like cobalt, iron, and nickel find application in magnetic resonance imaging (MRI) and magnetic data storage, technologies that require the concept of magnetism.
Alloying
Transition metals are naturally strong but they can become stronger when they form alloys with other metals. Moreover, alloying can also help to increase their resistance to corrosion.
What are the chemical properties of transition metals?
Variable oxidation states
Most transition metals have more than one oxidation state because of their partially filled d orbitals. These metals easily lose or gain electrons to form ions. Because of these characteristics, these metals are actively involved in catalysis and redox reactions.
Formation of colored ions
As electrons move from lower energy levels to higher energy levels within the d orbitals, they absorb light and appear colored. Some transition metals exhibit more than one color. This property contributes to their aesthetic appeal and makes them useful as pigments in paints.
Formation of colored complexes
Transition metals have large ionic charges but they form small cations, unlike other metals. Because of their partially filled or empty 3d orbitals, they can accept electrons from ligands and form complex ions.
Furthermore, these complexes may be coordination compounds with a central metal ion surrounded by ligands.
Catalysis
The partially filled d orbitals and the variable oxidation states these metals exhibit make them good catalysts. And, as catalysts, they also play key roles in redox reactions.
Transition metals can help lower the activation energy for a reaction by creating an alternative pathway, thereby increasing the rate of chemical reactions.
Reactions of transition metals
Redox reactions
Transition metals can lose and gain electrons and exhibit variable oxidation states. These properties make them important to oxidation-reduction reactions.
The rusting process of iron to iron oxide is a vivid example of oxidation-reduction reactions in transition metals.
4Fe (s) + 3O2 (g) ———> 2Fe2O3 (s)
Acid-base reactions
Transition metal form oxides and hydroxides that can behave like acids and bases. For example, chromium(III) oxide is a metal oxide and will react with acids to form salts.
Cr2O3 (S) + 6H2SO4 (aq) ———> 2Cr(HSO4)3 (S) + 3H2O (l)
Also, a metal hydroxide like aluminum hydroxide can act as a base and neutralize acids.
2Al(OH)3 (S) + 3H2SO4 (aq) ———> Al2(SO4)3 (S) + H2O (l)
Hydrogenation and dehydrogenation
Transition metals like platinum and palladium are catalysts for hydrogenation (addition of hydrogen) and dehydrogenation (removal of hydrogen) reactions, which are important steps in the production of various chemicals and fuels.
Precipitation reactions
Transition metal ions form insoluble precipitates with various anions. For example, in the reaction of silver nitrate with potassium chloride below. In qualitative analysis, precipitation reactions help to separate and identify ions in solutions.
AgNO3 (aq) + KCl (aq) ———> AgCl (s) + KNO3 (aq)
Redox titration
Transition metals can act as both the titrant (the substance added to the solution) and the analyte (the substance being analyzed) in redox titrations. In redox titrations, the transition metal in the analyte forms colored complexes.
Electrochemical reactions
Transition metals participate in electrochemical reactions, including corrosion and electroplating. Electroplating uses electric current to deposit a layer of metal onto another surface, thereby improving the appearance and preventing corrosion.
FAQs
Are all transition metals d-block elements?
All transition metals are d-block elements but not all d-block elements are transition metals. Elements of the d-block have partially filled d-subshells and can also form cations with partially filled d orbitals.
Which transition metals have a +1 charge?
Silver, copper, and mercury are the three transition metals that have a +1 charge. Silver (I) is the verified charge of silver. On the other hand, copper and mercury also form +2 ions.
How many transition metals have only one charge?
Fourteen transition metals tend to form only one charge.
In no particular order, they are scandium, zinc, silver, hafnium, nickel, zirconium, indium, yttrium, technetium, lutetium, cadmium, lawrencium, dubnium, and copernicium. However, some of them may exhibit other charges, but they are rare and highly unstable.
Can transition metals form covalent bonds?
Transition metals form covalent bonds with nonmetals when they are in their higher oxidation states.
Conclusion
The properties of transition metals make them different from other elements. Their unique physical properties, chemical properties, and the reactions they undergo make them valuable to different industries. From their multiple oxidation states and catalytic potential.
Also, transition metals find a wide range of applications from basic to advanced because of their strength, electrical conductivity, density, and malleability. Because of this, many buildings, equipment, chemicals, etc are made of at least one transition metal.
Finally, learn how to find the charge of the transition metals.
Thanks for reading.